Various forms of hoists heretofore have been provided for hoisting casing sections and the like into position relative to an oil well. However, most of these previously known forms of hoists have utilized lifting cables under the control of winches and are subject to malfunction and thus accidents sometimes occur adjacent an oil well when an hoist cable breaks.
Accordingly, a need exists for an improved form of hoist for operation immediately adjacent an oil well.
Examples of previously known forms of hydraulic lifting devices including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 3,768,578, 3,957,125, 3,958,376, 3,970,171.